Leaking Gutters and Downpipes: The Damp Wall Culprit

Article

What you are seeing

A damp patch on an inside wall that sits below a gutter joint, beside a downpipe, or on a chimney breast; peeling paint or blown plaster; stains that darken after rain and fade in dry weather. Outside you may see green algae, a dark streak on the brickwork, or a gutter holding water or leaves.

GOV.UK guidance describes penetrating damp as water entering from outside through defects in walls, roofs, windows or floors, and it is a different problem from condensation.

Rule these out first, cheapest first

Do these checks in a dry spell and again during rain.

1. Step 1, free: watch the gutter in the rain. From the ground, look for water spilling over the edge, dripping from joints or running down the wall. A short wait in heavy rain tells you more than a dry-day look.
2. Step 2, free: check the ground level. Is a drain or the gutter outlet blocked, with water pooling at the foot of the wall? Soil or paving piled above the damp-proof course lets water bridge it.
3. Step 3, low cost: clear and re-seal. Clear leaves from gutters and hoppers, tighten loose brackets and re-seal leaking joints. This is often a one-visit job for a handyman or roofer.
4. Step 4, trades: re-align or replace. Sagging gutters hold water and overflow, and cracked cast iron or plastic cannot be sealed for long. Replacement may be the only fix.
5. Step 5, wait: let the wall dry. A saturated wall can take weeks or months to dry once the water source is fixed. Good heating and ventilation help it along.
6. Step 6, only then: consider the air. Once the leak is fixed and the wall is drying, any remaining condensation can be dealt with separately.

The Ashford factor

Ashford is a wet part of Kent, and the Borough's own flood-risk assessment describes a river system of the Upper, Middle, East and Great Stour running through it. Whatever the weather does, gutters and drains that cannot carry a heavy downpour will spill it onto the wall and the ground at its foot.

Brick and ragstone walls absorb water and release it slowly, so a long-term leak can appear inside as a damp patch long after the cause started.

When a dehumidifier is not the answer

This is not a Dryzen problem. A dehumidifier lowers moisture in the air. It does not stop water entering a wall, and it cannot dry out the outer face of a wall that is being soaked from above. If you rent, report a leaking gutter to your landlord in writing.

Where Dryzen fits

A Dryzen system is a loft-mounted dehumidifier with insulated ductwork to the central area or stairway of the home. Each unit is rated for 150 square metres and has an extraction rate of 12 litres a day, and it uses about 20 pounds a year in energy. It suits owner-occupied homes with a loft. It is not suitable for rental properties unless the landlord authorises the changes. Once the gutters and walls are sorted, a survey can tell you whether any remaining dampness is condensation that a system could help with.

Quick questions

How do I tell a leaking gutter from condensation?

Leaks produce a patch with a defined edge that follows rain. Condensation appears in corners and on cold surfaces, and is worse on still, cold mornings.

Can I clear my own gutters?

Only if you can do so safely from a stable platform at a height you are comfortable with. For anything above ground-floor level, hire a professional.

How long does a wet wall take to dry?

It varies with the wall and the weather, and can take weeks to months. Heating and ventilation speed it up, but there is no quick fix.

Sources: GOV.UK: Understanding and addressing the health risks of damp and mould in the home; BRE: Diagnosing the causes of dampness in buildings; Ashford Borough Council: Strategic Flood Risk Assessment (2014)

Last reviewed 2026-10-05. General guidance only; this is not a survey of your home.